Homicide detectives are investigating a fatal shooting in the 2600 block of Black Fir Court in Reston. All parties are known to one another and there is no threat to public safety. pic.twitter.com/OXQZOJXG04

"He was very friendly. Played out at the [basketball] hoop all of the time. I am just sick about it," said a neighbor driving by the Fricker's house.

While police comforted the boy, neighbors saw another person who was injured come out on a gurney but could not tell who it was. That person has not been identified by police but is in critical condition.

Police say several people were inside the home when the shooting happened. Detectives were interested in a white Honda CRV with North Carolina plates. They took it away.

Neighbors said that Buckley Kuhn-Flicker's adult son arrived for the holidays on Thursday, and so did Scott Fricker's parents.

As investigators combed the crime scene for clues, a family dog was taken from the house to the animal shelter for safekeeping.

The Flickers attended a neighborhood holiday party recently, but there was no sign of trouble, according to neighbors.

One neighbor who did not want to be identified said he saw the grandmother hugging one of her grandchildren in such a way yesterday, which it now seems like a sign that something was terribly wrong.

Police said the shooter was known to the family and there is no public threat.